5:00 PM, 30,000 feet in the air. Peter Molyneux jumped on a flight back from Israel to England on the news that Curiosity, his experimental passion project, had just unexpectedly gone live on the App Store.

Desperate to see what was happening, he pressed his phone against the plane's tiny window, in the vain hope of getting some kind of signal.

The creator famed as much for his wild dreams and big promises as much for with his work at Lionhead seems to have been thwarted, just a little, by Apple's certification and release process. He'd thought he'd get more of a 24-hour window ahead of Curiosity's launch. "I woke up in Israel and I looked at my Twitters and they were live with people already tapping, so I just rushed to the airport and got on the first plane I could back to England."

The app gives participants an incredibly simple task: There's a black cube in a white room ("quite a beautiful-looking cube," Molyneux enthuses) that erodes as people around the world tap away at it in a race to see what's at its center. Only one person can attain the secret inside, and in typical Molyneux fashion, the creator has said that whatever the mystery is, it'll be completely transformative for the recipient.

"Firstly, it's amazing, and it's amazing by any scale," he says. "Secondly, that person's life will change forever."

Our phone conversation coincides with the clearing of the cube's first layer -- 100 million taps in less than 24 hours, he says. "What people do is they leave little messages around; they can tap away little messages," he says. "Some people leave artwork, some people do rude things, other people then turn those rude things into nice things."

The wonderment in his voice at the idea of thousands of people around the world tapping at Curiosity's black cube, at the potential to learn and study their behavior, is palpable. He sighs. When he talks about it, it's with the elegance of oratory, of someone who passionately believes in things bigger than himself. It becomes easy to see why the man known for over-promising so frequently can carry others away on the tide of his faith in possibility.

But how did that work on Apple? Molyneux says getting Curiosity certified was "pretty tough."

"It's very unique, it's very different, some of the tech in it is very unusual... It tests these very logical and very sensible guidelines that Apple has," Molyneux says.

The biggest issue in getting approval was that Apple demanded to know what was at the center of the cube, and Molyneux would not bend. "I've only told one other person in the world and I needed to tell that person to help me implement the video we're sending out," he says "If I tell somebody else... if it escapes out, it will ruin this simple, pure experiment."

"We're just asking: Is mystery and curiosity enough to drive people to do impossible things?"

Apparently. Molyneux says early response to Curiosity has surpassed all the expectations of his studio, 22Cans -- both abstractly and in terms of the technical architecture that underlies it.

"All of our systems are stretched and none of us have slept," he says. "We didn't expect this tidal wave of people."

In the end Apple consented to let Molyneux keep his mystery, so long as information about what Curiosity is was made clear in the app info. He says it has nothing to do with his career or his reputation.

"Apple doesn't have a clue who I am, and neither should they," Molyneux says. "I just explained -- 'Look, I can't tell you what is in there. You have to trust us that it is something amazing.'"

"They were very, very understanding," he continues. "They could have easily turned around and said, 'You know what? Why should we take the risk?' But I think they saw it was the use of mobile in a completely different way... It took us about four weeks to get through, but we did get through."

Requested revisions mainly hinged on terms and conditions, and some aspects of the free game's shop, which includes upgraded taps that players can buy through in-app purchases. "And this is the first time we've ever submitted any app to the App Store, so there were a number of schoolboy errors we made in the first instance," he says. "They went as fast as I think they could. I think it's amazing you can get through so quickly."

Now that Apple has consented to play host to Molyneux's experiment (the app is also available on Android), the first challenge is managing traffic. "My expectation was we would get a few thousand people and they would tap for maybe a minute, and then say, 'Oh, that's interesting, I'll check back tomorrow and have a look at it," he says. "Instead what we found was there aren't a few thousand -- there's a few hundreds of thousands of people, and the people who are joining the cube aren't tapping for a few minutes, they're tapping for a few hours, and they're creating this living piece of art, almost."

"It's way, way more than we ever dared hope or expect," he adds. "This is an experiment... It's a game, it's a graffiti board, it's a living thing. The trouble is our servers, designed for tens of thousands for people, are struggling to keep up. None of us went home last night."

A fix -- and further announcements about Curiosity -- are imminent, says Molyneux. But once the server crunch goes away, the analytics can begin. "The fascinating thing is, why do people start [tapping] in the middle and then spread out? There's no rule to do that, so we want to say why, when people reveal a tiny bit of the surface below, do people start in the middle and spread out? What do the taps mean?"

"We want to share all that data, and share the instruction... what we're doing with that data, and that's when I think it gets really fascinating," he enthuses. "A little bit later we're going to be using some of that Facebook data which people have allowed us to use, and use it to enhance the experience. We're going to be changing some rules; our first rule change will probably come next week, and that'll be really exciting. All of this exciting stuff is yet to be."

It's working, he says. Only two people in the world might know what's really inside the cube, and whether it'll be as momentous a discovery as Molyneux promises. But for now he's the one having his expectations surpassed. "It's amazing," he says. "We've got tons of graphs and data coming in, and looking at that is the most inspirational thing I have seen as a game designer, ever."